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Dobs

2,000 RPM idle driving me nuts!

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After 115,000 miles with everything running perfectly, I stripped everything down my VFR 1200 to change the plugs and check the valve clearances.  The old plugs were a perfect light-brown color and all valve clearances were within spec.

 

I re-assembled everything, replacing the throttle body as a proactive measure, with a pristine unit I bought from eBay a few years ago.  I also replaced the air filter element with a new OEM element.  When I fired the bike up, it idled at 2,000 RPM.  Thinking it might be due to the new air filter and that the ECU might need to re-learn something, I removed the battery for an hour and then took the VFR on a long (180 mile) ride.  On the way home, the idle was even higher (around 2,500 RPM).  I then assumed that there must be a problem with the newer throttle body so I put the original back on.  No difference.  Suspecting I may have a vacuum leak around the aging intake rubber insulators (the rubber circular mounts for the throttle body) I replaced them.  I also found a heavily-discounted new MAP sensor on eBay so bought and installed that too.  While I had the throttle body off to install the new insulators, I opened up the valve covers again just to double check the clearances and to to make sure there were no valve cover gasket issues.

 

You can imagine my disappointment when I started up after replacing the insulators and MAP sensor and the idle was still around 2,000 RPM.

 

Any suggestions?  The ECU is supposed to keep the idle at around 1,100 RPM.  Anyone know how it does this?  Any way to force a re-learn?

 

Graham

 

 

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I would recommend downloading the 2014 shop manual available in the recent top download section in the right column on the home page.

 

Then I would follow the procedure for synchronizing the starter valves outlined on page 7-20.  I purchased a motion pro vacuum gauge a few years back for this job and it works well, however if you don't use it very much, the medium can evaporate out.  If that happens, the next time you want to use it you have to purchase new medium from motion pro.  Now when I use it, I load the medium, use it, then remove the medium and return it to the bottle for future use.

 

After you get your starter valves setup, go to page 3-12 for instructions on how to manually set your idle speed.  I have a 5th gen and the procedures are pretty much the same.  I did this after a valve adjust last year and it now runs like a top.

 

Good luck.

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1 hour ago, Dobs said:

 

  The ECU is supposed to keep the idle at around 1,100 RPM.  Anyone know how it does this?  Any way to force a re-learn?

 

Graham

 

 

It can only do that if everything is in good nick . . . FSM mentions checking the throttle freeplay - make sure no changes were made and everything is connected correctly.  In these instances I would not assume it was done properly - follow the manual.  Secondly and maybe more likely check for a vacuum leak(s).  Unmetered air entering will not be measured by the ECU and you'll get idle and performance issues from it.  The aforementioned starter valve synch will reveal a leak and is good practice, particularly on your ebay sourced T/B. 


Best of luck sorting it.

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Edit: sorry, I just realized I had not stated that I have a VFR 1200.  I've edited the original post too.

 

Thanks guys.  @Fritzer, I don't see a download for the 2014 VFR 1200, just for the VFR800.  As far as I know, the VFR1200 doesn't have a manual idle adjustment.   On page 6-78 of the 2010 VFR1200 service manual under "Idle Speed Inspection":

"This system eliminates the need for manual idle speed adjustment compared to previous designs".

 

@Cogswell, I blocked off the throttle openings with 50mm rubber stoppers, taped off the small bypass holes, attached a hose to the MAP hose, and gently blew into the hose (don't have a smoke machine).   I could not hear any hissing and felt no give when blowing (no air leaking).  I know this is not very scientific but I don't think I have a vacuum leak (and definitely not a major one), especially after changing the intake insulators. 

 

 

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5 hours ago, Fritzer said:

I would recommend downloading the 2014 shop manual available in the recent top download section in the right column on the home page.

 

Then I would follow the procedure for synchronizing the starter valves outlined on page 7-20.  I purchased a motion pro vacuum gauge a few years back for this job and it works well, however if you don't use it very much, the medium can evaporate out.  If that happens, the next time you want to use it you have to purchase new medium from motion pro.  Now when I use it, I load the medium, use it, then remove the medium and return it to the bottle for future use.

 

After you get your starter valves setup, go to page 3-12 for instructions on how to manually set your idle speed.  I have a 5th gen and the procedures are pretty much the same.  I did this after a valve adjust last year and it now runs like a top.

 

Good luck.

Hi Fritzer. Think your referring to the 8gen. Dobs bike is the VFR1200  No Starter Valves in that beast. Good advice for the 8gen though.:fing02: 

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I guess I am getting old and dyslexic😊  Thought I read that he had a 8th gen.

 

Sorry

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The dead give away of an air leak on a Fi engine is high uncontrolled
idle... on a fuel injection system *any* air that gets past the
throttle bodies the map just adds the corresponding fuel... the result
is high uncontrollable idle... make sure all the rubber hoses are
connected and in good shape... make sure all the intake boots are
tight and in good flexible shape... if the rubbers are hard and
cracked its time for replacement...

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2 hours ago, BusyLittleShop said:

The dead give away of an air leak on a Fi engine is high uncontrolled
idle... on a fuel injection system *any* air that gets past the
throttle bodies the map just adds the corresponding fuel... the result
is high uncontrollable idle... make sure all the rubber hoses are
connected and in good shape... make sure all the intake boots are
tight and in good flexible shape... if the rubbers are hard and
cracked its time for replacement...

Thanks for your post @BusyLittleShop  I replaced the intake rubber boots and o rings and did my crude check for leaks.  I guess it might be time to buy a smoke machine.  

I notice that the butterflies open very slightly (perhaps an 1/16") when the ignition is turned on.  Should they be totally closed or is this normal?

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Not  sure on VFR1200  series, I never did any work on them. But you did say you swapped the throttle bodies. Correct me if I'm wrong, but the VFR1200 has a TPS sensor.. TPS- thottle position sensor. Has that been set according to your engine ? 

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39 minutes ago, TheDutchy said:

Not  sure on VFR1200  series, I never did any work on them. But you did say you swapped the throttle bodies. Correct me if I'm wrong, but the VFR1200 has a TPS sensor.. TPS- thottle position sensor. Has that been set according to your engine ? 

There's nothing in the service manual about calibrating the TPS.  I wonder if there is a dealer-only service manual with more info.

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It mite be a good time, if not already to download the FSM here:   https://www.vfrdiscussion.com/index.php?/files/

 

Since you reported that the engine ran perfectly for 115,000 miles and is now exhibiting this behavior with two different T/B units, it would seem something untoward happened elsewhere during the service.  The manual states this about idle speed:

image.png.d8eb4f6842b46a24b17ad85f6b0ee6b8.png

It could be something simple such as the crankcase breather hose was overlooked, or two hoses got mixed up, etc.   The manual can help you retrace your steps in removal / re-installation and possibly help you sort it. 

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Could this be missing/faulty engine temperature sensor resulting in mis-adjusted idle?

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1 hour ago, RC36B said:

Could this be missing/faulty engine temperature sensor resulting in mis-adjusted idle?

Would that not cause the MIL to come on?  I've checked for DTC error codes are there aren't any.  Thanks for the suggestion though.

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58 minutes ago, Dobs said:

Would that not cause the MIL to come on?  I've checked for DTC error codes are there aren't any.  Thanks for the suggestion though.

Well, by your logic, then you don't have a problem because their is no error code. 🙂

 

I think you need to turn the problem upside down - even you don't have an error code, it is clear you have a problem. A sensor can fail so that it is not detected, a short somewhere etc. So everything is a "suspect"!

 

Air leaks would be high on my list - it has already been suggested and you ruled it out.

 

From you description it appears as the ECU does not adjust idle at all - as indicated by engine revving even higher when engine is warm.

 

 

 

 

 

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Reset the ECU

 

Disconnect the battery for a few minutes. Reconnect, then start the bike and let it run until the operating temp gets high enough to kick in the cooling fan and turn
off. Let it cool down. The key is to not touch the throttle at any time during this cycle, including when
starting the bike. Just press the button.

 

If that does not work, go back to your old throttle body and retest....
 

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Folks,

 

It's fixed!

 

Thanks for all your suggestions.  Sorry for the delay in replying.  I to wanted to get to the bottom of this before replying.

Since my last post (with the eBay throttle body on) I tried disconnecting the battery before running the bike for 15 minutes without touching the throttle.  This made no difference.  I then put my original throttle body back on and did the same procedure.  No difference.  Worrying that one of my cam sprockets might be off a tooth, causing low vacuum due to valve timing being off, I tore everything down again, removed the valve covers and checked the sprocket alignment marks.  Both sprockets were fine. I also checked electrical continuity between all sensors and the ECU multi-pin connectors.

Having ruled out MAP sensor, IAT sensor, air leak and valve timing, I turned to a problem with the ECU or throttle body.  I decided to take the bike to my local Honda dealership in case their HDS could diagnose an issue or recalibrate the idle.  I put the newer (eBay) throttle body back on (I thought, if calibration is possible, I may as well have the newer body calibrated) and went to the dealership this afternoon.

It turns out (not what I was told by the service dept a few weeks ago) that the HDS (Honda Diagnostic System) can reset TCP and/or TP values.  The tech discovered that the "TP SENSOR 1 (Angle)" and "TP SENSOR 2 (Angle)" values were at 2 degrees when the target is 1 degree.  The ECU thought I twisting the throttle by 1 degree and opened the butterflies slightly.  After recalibrating the sensor voltages, they now both read 1 degree.  Idle is now down to just above 1100 RPM.  Yay!  I now suspect that installing the throttle body from eBay changed voltage reference values in the ECU that were not reset by installing the original body.  Even though the service manual states that idle can't be adjusted and is set automatically by the ECU, it is possible for a dealer to recalibrate the throttle body with HDS.

 

I've attached the before and after HDS print-outs.  

 

Thanks again for all your advice.

 

Before calibration:

Image (96).jpg
After calibration:

Image (97).jpg

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Hi Dobs. That's great news, and thanks for the detailed description and fix to your problems, glad you were able to get the before and after HDS printouts.

Cheers.

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